Method for packet transmission of data

ABSTRACT

A method provides packet transmission of data between two terminal devices via at least one flying object. The flying objects are moving within a given swarm of flying objects and the flying objects are disposed in a grid being characterized by a number of flight paths. One flying object from the swarm of the flying objects is determined to be a reference flying object and each of the flying objects is assigned a position. Coordinate values of a receiving flying object within the swarm of the flying objects is derived from a respective data packet being transmitted. A number of sequential single transmissions for a transmittal of data between a transmitting flying object and the receiving flying object is performed. Each single transmission within the swarm of the flying objects occurs only between two respective flying objects which are topologically neighboring and in direct communication with each other.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority, under 35 U.S.C. § 119, an Austrianapplication AT A50262/2019, filed Mar. 26, 2019; the prior applicationis herewith incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a method for packet transmission of databetween at least two terminal devices via at least one flying objectaccording to the independent apparatus claim and a method for packettransmission of data between at least two terminal devices via at leastone satellite according to the independent method patent claim.

In presently known communication systems which enable a datatransmission by means of flying objects, a bidirectionaltelecommunication between two terminal devices located on the ground isproduced through a flying object, such as a satellite. In this process,a link is established, for example from a satellite telephone to acommunications satellite, such as a geostationary satellite, and thedata transmission occurs directly from the transmitter to the receiverthrough this geostationary satellite. However, the coverage in the polarregions may be greatly restricted or entirely absent. Alternatively, adata transmission can also occur from the transmitter to a satellite,which transmits the data to one or more other non-geostationarysatellites, which relay the data back to the receiver on the ground. Forthis purpose, satellite constellations are used, i.e., a number ofmutually coordinated satellites, which encircle the earth in the samedirection at a constant distance from the earth, such as Walker polarconstellations. The data being relayed is forwarded by a known packetswitching process from one satellite to the next within the satelliteconstellation. The target address of a particular data packet isdetermined in this case with a longest prefix match method, for example,based on the target address transmitted with the respective data packet.Since the transmission pathways are not fixed, however, some of thesatellites serving as switching stations may become overloaded.

BRIEF SUMMARY OF THE INVENTION

The problem which the invention proposes to solve is therefore toprovide a simple method for the packet transmission of data betweenflying objects which assures a fast relaying of the data packets to areceiving flying object and at the same time avoids the known drawbacks.

The invention solves this problem with a method for packet transmissionof data between at least two terminal devices via at least one flyingobject according to the independent apparatus patent claim.

According to the invention, it is provided that:

a) the flying objects are moving within a given swarm of flying objects,

b) the swarm of flying objects contains a number of flying objects whichare respectively moving on flight paths, especially closed flight paths,

c) wherein the individual flying objects are arranged in a grid which ischaracterized by a number of flight paths,

d) a number of flying objects are moving in succession, especiallyequidistant from each other, on each flight path, so that each of theseflying objects of the flight path is in respective communication with apreceding flying object and a following flying object,e) the individual flying objects are moving on multiple flight pathssuch that each time there are arranged in a given orientation to arespective flight path an associated neighboring flying object of aright-hand neighboring flight path looking in the flight direction andan associated neighboring flying object of a left-hand neighboringflight path looking in the flight direction and in particular they arein communication with the respective flying object for at least aportion of the flight path,f) one flying object from the swarm of flying objects is determined tobe a reference flying object,g) each of the flying objects is assigned a position, especially atwo-dimensional position containing multiple, especially two coordinatevalues within the swarm of flying objects based on its position relativeto the reference flying object,

gi) wherein those flying objects which are situated on the same flightpath are assigned the same coordinate value of the first coordinate,

gii) wherein those flying objects which are in communication with eachother as associated neighboring flying objects of a left-hand and aright-hand neighboring flight path are assigned the same coordinatevalue of the second coordinate,

h) the coordinate values of a receiving flying object within the swarmof flying objects are derivable from a respective data packet beingtransmitted,

i) a number of sequential single transmissions is performed for thetransmittal of data between a transmitting flying object and a receivingflying object,

ii) wherein each single transmission within the swarm of flying objectsoccurs only between two respective flying objects which aretopologically neighboring and in direct communication with each other,and

j) during the process of the single transmission from the respectiveflying object where the data packet is located that is beingtransmitted, a topologically neighboring flying object is selected,especially a neighboring flying object or preceding flying object orfollowing flying object, with the aid of which the coordinate value ofthe receiving flying object which is derivable from the data packet isselected and the data packet is sent to this selected neighboring flyingobject.

This procedure makes it possible to assign characteristic coordinatevalues or identifiers to flying objects within a swarm of flyingobjects, wherein the coordinate values of a receiving flying object canbe derived from the data packet being transmitted. Thus, advantageously,information about the layout of the swarm of flying objects or itsdimensions, the number of flight paths and the number of lines ofmutually neighboring flying objects is sufficient for a quick relayingof the data packets.

This procedure is advantageously not tied to a particular setting or aspecial type of flying objects and it can be used in different fieldswith variable network topology, where the relations between neighboringelements remain unchanged.

An especially simple data relaying between terminal devices positionedon the ground by means of a swarm of flying objects can be accomplishedif:

a) at least two terminal devices positioned on the ground are broughtinto communication respectively with at least one of the flying objectsfrom the swarm of flying objects, each of the terminal devices beingassigned respectively one communication address, especially a distinctaddress,b) wherein a data packet is sent from one of the terminal devices as atransmitting terminal device to the respective other terminal device asa receiving terminal device, the data packet containing a communicationaddress assigned to the receiving terminal device,c) wherein the data packet is relayed by the transmitting terminaldevice to one of the flying objects as a transmitting flying object,d) wherein a receiving flying object is determined by the transmittingflying object, which stands in data communication with the receivingterminal device,e) wherein the data packet is relayed from the transmitting flyingobject to the receiving flying object according to the invention, andf) wherein the data packet is relayed from the receiving flying objectto the receiving terminal device.

In the case of a longer lasting conversation or a data transmittalrequiring a longer time, an especially fast and reliable determinationof the receiving flying object can be assured if:

a) the individual flying objects of the swarm of flying object aredivided into clusters, each time one of the flying objects of thecluster being determined to be a cluster registration flying object,

b) wherein individual terminal devices which stand in data communicationwith a flying object of the cluster are registered through this flyingobject with the cluster registration flying object,

c) wherein in the event that a data link is to be established accordingto the invention:

ci) a query is sent from the transmitting flying object to theindividual cluster registration flying objects as to whether theparticular receiving terminal device stands in a data link with a flyingobject associated with this cluster registration flying object, and

cii) any coordinate values, especially the two-dimensional coordinatevalues of the receiving flying object regarding the query are sent backby the cluster registration flying object to the transmitting flyingobject based on this query, and

d) a data link is established by the transmitting flying object to thereceiving flying object having so reported back, in order to bring aboutthe data communication.

The invention furthermore relates to a method for packet transmission ofdata between at least two terminal devices via at least one satellite:

a) wherein the satellites are moving within a given satelliteconstellation around the earth,

b) wherein the satellite constellation contains a number of satelliteswhich are respectively moving on a non-geostationary orbit around theearth,

c) wherein the individual satellites are arranged in a grid which ischaracterized by a number of orbits, and

d) wherein an orbit extends respectively in a circle or ellipse aroundthe earth, especially on one side of the earth from a first pole to anopposite second pole and then on the other side of the earth from thesecond pole to the first pole,

e) wherein a number of satellites are moving in succession, especiallyequidistant from each other, on each orbit, so that each of thesesatellites of the orbit is in respective communication with a precedingorbital satellite and a following orbital satellite,f) wherein the individual satellites are moving on multiple orbit, suchthat each time there are arranged in a given orientation to a respectiveorbit an associated neighboring satellite of a right-hand neighboringorbit looking in the flight direction and an associated neighboringsatellite of a left-hand neighboring orbit looking in the flightdirection and in particular they are in communication with therespective satellite for at least a portion of the orbit,g) wherein one satellite from the satellite constellation is determinedto be a reference satellite,h) wherein each of the satellites is assigned a position, especially atwo-dimensional position comprising multiple, especially two coordinatevalues within the satellite constellation based on its position relativeto the reference satellite,

hi) wherein those satellites which are situated on the same orbit areassigned the same coordinate value of the first coordinate,

hii) wherein those satellites which are in communication with each otheras associated neighboring satellites of a left-hand and a right-handneighboring orbit are assigned the same coordinate value of the secondcoordinate,

i) wherein the coordinate values of a receiving satellite within thesatellite constellation are derivable from a respective data packetbeing transmitted,

j) wherein a number of sequential single transmissions is performed forthe transmittal of data between a transmitting satellite and a receivingsatellite,

ji) wherein each single transmission within the satellite constellationoccurs only between two respective satellites which are topologicallyneighboring and in direct communication with each other,

k) wherein during the process of the single transmission from therespective satellite where the data packet is located that is beingtransmitted, a topologically neighboring satellite is selected,especially a neighboring satellite or preceding satellite or followingsatellite, with the aid of which the coordinate value of the receivingsatellite which is derivable from the data packet is selected and thedata packet is sent to this selected neighboring satellite.

This procedure makes it possible to assign characteristic coordinatevalues or identifiers within the satellite constellation to individualsatellites. These coordinate values or identifiers can be used insatellite-specific or satellite constellation-specific prefixes for theIP addresses of the hosts and routers on board the satellites within thesatellite constellation. In this way, the coordinate values of areceiving satellite are easy to derive from the data packet beingtransmitted.

Thus, advantageously, information about the layout of the satelliteconstellation or its dimensions, the number of orbits and the number oflines of mutually neighboring satellites is sufficient for a quickrelaying of the data packets being transmitted from a transmittingsatellite in a series of single transmissions between respectiveneighboring satellites to the receiving satellite.

An especially simple data transmission between terminal devicespositioned on the ground via a satellite constellation can beaccomplished if:

a) at least two terminal devices positioned on the ground are broughtinto communication respectively with at least one of the satellites ofthe satellite constellation, each of the terminal devices being assignedrespectively one communication address, especially a distinct address,b) wherein a data packet is sent from one of the terminal devices as atransmitting terminal device to the respective other terminal device asa receiving terminal device, the data packet containing a communicationaddress assigned to the receiving terminal device,c) wherein the data packet is relayed by the transmitting terminaldevice to one of the satellites as a transmitting satellite,d) wherein a receiving satellite is determined by the transmittingsatellite, which stands in data communication with the receivingterminal device,e) wherein the data packet is relayed from the transmitting satellite tothe receiving satellite according to the invention, andf) wherein the data packet is relayed from the receiving satellite tothe receiving terminal device.

A quick relaying of the data being transmitted is facilitated, since thetransmitting and receiving terminal devices each have a communicationaddress which is characteristic of a position on the earth and whichcontains for example no coordinate values which are used for therelaying of data packets between satellites.

Since a fixed communication address is assigned to the receivingterminal device for the time during which it is in data communicationwith the satellite constellation and this is relayed along with the datapacket being transmitted, that receiving satellite which is currently indata communication with the receiving terminal device can advantageouslybe determined in reliable manner, so that the data packet can be relayedquickly to it based on the coordinate values assigned to this receivingsatellite within the satellite constellation.

In the case of a longer lasting conversation or a data transmittalrequiring a longer time, an especially fast and reliable transmittal ofdata packets between terminal devices positioned on the earth by meansof satellites can be accomplished if:

a) the individual satellites in the satellite constellation are dividedinto clusters, each time one of the satellites of the cluster beingdetermined to be a cluster registration satellite,

b) wherein individual terminal devices which stand in data communicationwith a satellite of the cluster are registered through this satellitewith the cluster registration satellite,

c) wherein in the event that a data link is to be established accordingto the invention:

ci) a query is sent from the transmitting satellite to the individualcluster registration satellites as to whether the particular receivingterminal device stands in a data link with a satellite associated withthis cluster registration satellite, and

cii) any coordinate values, especially the two-dimensional coordinatevalues of the receiving satellite regarding the query are sent back bythe cluster registration satellite to the transmitting satellite basedon this query, and

d) a data link is established by the transmitting satellite to thereceiving satellite having so reported back, in order to bring about thedata communication.

Within such a cluster in the satellite constellation, the individualsatellites relay information as to whether a terminal device iscurrently in data communication with them to the cluster registrationsatellites. Thus, by a query to the cluster registration satellites, thecoordinate values of the receiving satellite which is in datacommunication with the receiving terminal device can be determinedespecially quickly.

The terminal devices positioned on the earth or the ground can be mobileterminal devices such as mobile or satellite telephones or alsostationary terminal devices such as ground stations. Such mobile orstationary terminal devices may differ in the type of link to asatellite or a flying object. For example, mobile transmitting andreceiving terminal devices can be connected by means of user links toflying objects or satellites, while stationary terminal devices such asground stations can be connected via feeder links. However, such adistinction in the link is in no way mandatory for the feasibility of amethod according to the invention.

Basically, for example, the following transmission paths are possible ina method for packet transmission of data according to the invention: oneor more mobile transmitting terminal devices and one or more mobilereceiving terminal devices within the satellite constellation or theswarm of flying objects are in communication with the same or differentsatellites or flying objects.

In this case, for example, data being relayed is sent from atransmitting terminal device by means of a transmitting satellite, withwhich the transmitting terminal device is in data communication, to thereceiving satellite which is in communication with the receivingterminal device, and then relayed from the receiving satellite to thereceiving terminal device.

One or more mobile transmitting terminal devices within the satelliteconstellation or the swarm of flying objects are in communication withthe same or different satellites or flying objects, while one or morestationary terminal devices or ground stations are in communication withsatellites or flying objects and in addition with a terminal device,such as the public Internet, which is not connected directly to thesatellites or flying objects.

In this case, for example, data is sent from the transmitting terminaldevice via a transmitting satellite to a receiving satellite, in whosecoverage territory the ground station is located, and which is connectedvia its feeder link to the ground station, and relayed further to theground station. The data is then relayed from the ground station to thefurther receiving terminal device.

One or more stationary terminal devices or grounds stations within thesatellite constellation or the swarm of flying objects are incommunication with the same or different satellites or flying objects,and in addition with a transmitting terminal device that is notconnected directly to the satellites or flying objects, while one ormore mobile receiving terminal devices are likewise in communicationwith satellites or flying objects.

In this case, for example, data is sent from the transmitting terminaldevice via the ground station to a transmitting satellite, in whosecoverage territory the ground station is located. The data is thenrelayed to a receiving satellite, which is connected via its user linkto the receiving terminal device, and sent on further to the receivingterminal device.

As a further variant, both a mobile transmitting terminal device and amobile receiving terminal device may each be in communication with aground station, and each time only the ground stations are incommunication with the satellites of the satellite constellation or theflying objects of the swarm of flying objects.

In this case, for example, data is sent from the mobile transmittingterminal device via a first ground station to a transmitting satellite,in whose coverage territory the first ground station is located. Thedata is then relayed to a receiving satellite, in whose coverageterritory a second ground station is located, which is in communicationwith the mobile receiving terminal device. The data is further sent fromthe receiving satellite, which is connected by its feeder link to thesecond ground station, to the second ground station and then relayedfrom this to the mobile receiving terminal device.

Further benefits and embodiments of the invention will emerge from thedescription and the accompanying drawings.

The invention is represented schematically in the following with the aidof especially advantageous, but not limiting exemplary embodiments inthe drawings, and it shall be described as an example with reference tothe drawings.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin a method for packet transmission of data, it is nevertheless notintended to be limited to the details shown, since various modificationsand structural changes may be made therein without departing from thespirit of the invention and within the scope and range of equivalents ofthe claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a schematic representation of orbits along which a number ofsatellites are circling the earth;

FIG. 2 is an illustration showing a detail view of a gridlike satelliteconstellation of FIG. 1;

FIG. 3 is a block diagram showing a course of a data transmission in asegment of the satellite constellation of FIG. 1 and FIG. 2;

FIG. 4 is an illustration showing an example of a partitioning of thesatellite constellation of FIG. 1 and FIG. 2 into clusters; and

FIG. 5 is a schematic representation of a swarm of flying objects movingalong flight paths.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures of the drawings in detail and first,particularly to FIG. 1 thereof, there is shown a schematicrepresentation of a satellite constellation, such as can be used for amethod according to the invention for a packet transmission of data.Satellites S move here within this predetermined satellite constellationaround the earth E, which is shown schematically as a sphere in FIG. 1.The satellite constellation contains a plurality of satellites S, eachof them moving on a non-geostationary orbit O₁, . . . , O₅ or trajectoryaround the earth E. In the exemplary embodiment shown, low earthorbiting (LEO) satellites are used, i.e., satellites moving in lowtrajectories around the earth.

While the area covered by an individual satellite S within such asatellite constellation is smaller in comparison to the coverage of ageostationary satellite, the satellite constellation contains a largenumber of satellites S, which move around the earth at great angularvelocity, so that a continuous area coverage is assured, even in thepolar regions.

The method according to the invention can be used basically withsatellite constellations having different orbital structures, whosetopology is similar to a Walker constellation. Within such a Walkerconstellation, for example, all orbits O₁, . . . , O₅ have the sameorbital inclination relative to a reference plane, and the equatorialplane can be used for example as the reference plane.

In the exemplary embodiments in FIGS. 1 to 4, the satelliteconstellation is such a Walker constellation. The Walker star satelliteconstellation in FIGS. 1 to 4 contains for example 50 satellites, whereten satellites S each are moving on five orbits O₁, . . . , O₅ at analtitude of around 780 km with a velocity of around 27,000 km andorbital periods of around 100.5 minutes. The radius of the region onearth that is covered by these satellites is around 2200 km. Astationary or mobile terminal device on the earth thus remains for a fewminutes within the region covered by a single satellite.

Within the satellite constellation, the individual satellites S arearranged in a grid, which is characterized by a number of orbits O₁, . .. , O₅ or trajectories. Each orbit O₁, . . . , O₅ describes a circulartrajectory, which extends e.g. on one side of the earth from north tosouth and then on the other side of the earth from south to north,thereby forming a closed circular trajectory. The orbits O₁, . . . , O₅can intersect each other in a star shape above the geographical southpole SP and the geographical north pole NP, as can be seen in FIG. 2.

In the exemplary embodiment of FIG. 2, a representation of such asatellite constellation with five orbits O₁, . . . , O₅ and sixsatellite lines LOS₁, . . . , LOS₆ is shown schematically. In theexemplary embodiment of FIG. 2, the orbits O₁, . . . , O₅ cross eachother in a star pattern in the region of the south pole SP and the northpole NP. If a satellite S for example finds itself on the orbit O₂westward or to the left of the orbit O₃, which is represented in FIG. 2as a straight line, and is approaching the geographical north pole NPfrom the geographical south pole SP, the distance between the orbit O₂and the orbit O₃ will decrease until it crosses the orbit O₃ above thenorth pole NP and the satellite S continues its movement on the orbit O₂eastward or to the right of the orbit O₃. The satellite S then movesfurther on the orbit O₂ eastward or to the right of the orbit O₃, untilit finally reaches the geographical south pole SP, where the orbit O₂again crosses the orbit O₃ and the satellite S then continues itsmovement westward or to the left of the orbit O₃. The satellites arearranged on the individual orbits O₁, . . . , O₅ such that they crossthe north pole NP and the south pole SP slightly staggered in timeand/or altitude, so that a collision is ruled out.

On each of the orbits O₁, . . . , O₅ a plurality of satellites S aremoving, being arranged at equal distances in succession in the exemplaryembodiment shown. This equidistant arrangement, however, is in no waymandatory, and the method for data transmission according to theinvention can also be implemented with a different satellitearrangement, so long as it produces a basically gridlike arrangement ofthe satellites S, in which each satellite S maintains its positionwithin the grid of orbits O₁, . . . , O₅ and satellite lines LOS₁, . . ., LOS₆, i.e., coordinate values within the satellite constellation.

Each of the satellites S of an orbit O₁, . . . , O₅ stands incommunication respectively with a preceding orbital satellite and afollowing orbital satellite. This means that a particular satellite Sstands in communication each time with the satellite in front of it andthe satellite behind it on the particular orbit O, looking in the flightdirection.

The individual satellites S move on multiple orbits O₁, . . . , O₅, sothat in a given orientation to the respective orbit O underconsideration each satellite on the particular orbit O is associatedwith an associated neighboring satellite of a right-hand neighboringorbit, e.g., situated eastward of the particular orbit O, and anassociated neighboring satellite of a left-hand neighboring orbit, e.g.,situated westward of the particular orbit O. A respective neighboringsatellite S stands in communication with its associated neighboringsatellite at least for a portion of the orbit O, for example, outsidethe polar regions.

At the seam, i.e., at the margin of the satellite constellation, wherethe orbits O₁ and O₅ are situated in the exemplary embodiment shown,each satellite S stands in data communication only with an associatedneighboring satellite of a right-hand or left-hand neighboring orbit, inaddition to its preceding orbital satellite and its following orbitalsatellite.

Each satellite S, moving for example on the orbit O₁, stands incommunication only with the satellite situated respectively in front ofit and behind it in the direction of flight, and an associatedneighboring satellite of the right-hand neighboring orbit, situatedeastward of the respective orbit O₁, in this case being the orbit O₂.Each satellite S, moving on the orbit O₅, stands in communication onlywith an associated neighboring satellite of the left-hand neighboringorbit, situated westward of the respective orbit O₅, in this case beingthe orbit O₄, in addition to its preceding orbital and its followingorbital satellite.

Within a satellite constellation with satellites S in near-earthtrajectories, the satellites S usually stand in communication with eachother by high-frequency or optical intersatellite links. Such satellitesS may also have user links and feeder links, i.e., transmitting andreceiving links for mobile terminal devices or stationary terminaldevices such as base stations, stationed on the earth. Such linksusually support network protocols such as IP protocols.

User and feeder links are transmitting and receiving links,respectively, which are used for different purposes. User links are usedfor mobile user terminal devices, such as satellite telephones, andfeeder links are used for data links to stationary terminal devices suchas ground stations of a satellite operator. Ground stations are usuallypresent only at a few selected locations on the earth E. They serve forrelaying data between the satellite constellation and the terrestrialInternet, for example, and for monitoring and control of the satellitesS by the satellite operator. User and feeder links may also beconfigured alternatively as combined links. A method for packet datatransmission according to the invention is possible with no problems forboth forms of configuration.

As can be seen in FIG. 2 and FIG. 3, each of the satellites S isassigned coordinate values within the satellite constellation based onits position within the grid of orbits O₁, . . . , O₅ and satellitelines LOS₁, . . . , LOS₆. In the exemplary embodiment shown in FIG. 3,there are specifically two coordinate values which indicate atwo-dimensional position within the satellite constellation.Alternatively, the position information may also comprise only onecoordinate value, or more than two coordinate values.

One satellite S of the satellite constellation is determined to be areference satellite. In the exemplary embodiment, the satellite Ssituated in the grid of FIG. 3 on the first orbit O₁ and the satelliteline LOS₁ is determined to be the reference satellite and it is assignedthe coordinate value (1,1) based on its position in the satelliteconstellation. Those satellites S which are situated on the same orbitO₁, . . . , O₃ are assigned the same coordinate value of the firstcoordinate, while those satellites S which are moving respectively onthe left-hand or right-hand neighboring orbits and stand incommunication with a particular satellite S are assigned the samecoordinate value of the second coordinate.

Now, if a transmitting satellite TS receives a data packet to betransmitted, it will derive the coordinate values of the receivingsatellite RS within the satellite constellation from the target addressof the data packet being transmitted. No routes are stored on therouters aboard the satellite S. Instead, the data packet is routed withthe aid of an algorithm and with the aid of the extracted targetcoordinates.

The routing of the data packets occurs dynamically, for example with theaid of a heuristic algorithm for finding a path in an undirected graphon a sphere or a portion of a sphere. Different kinds of algorithm canbe implemented, such as the preferring of horizontal or vertical pathson the basis of the extracted coordinate values or target coordinates ofthe particular data packets. Base stations or transmitting terminaldevices SE and receiving terminal devices EE on the earth E have no suchcoordinate information in their IP addresses.

For example, each satellite S starting with the transmitting satelliteTS can compute the Manhattan distance, e.g., as described athttps://de.wikipedia.org/wiki/Manhattan-Metrik orhttps://en.wikipedia.org/wiki/Taxicab_geometry, each of them retrievedon 20 Feb. 2019, between itself and the receiving satellite RS. Thetransmitting satellite TS then sends the data packet, taking intoaccount e.g. the configured ISL preference, i.e., horizontal orvertical, and the availability of the preferred ISL, to the nextsatellite S via this ISL. If this ISL is not available, the next bestISL in terms of the Manhattan distance is chosen.

If this ISL also is not available, the ISL will be chosen that isopposite the first chosen ISL. If this one also is not available, theISL which is opposite the second optimal ISL will be chosen. In no case,however, will a packet be relayed on the ISL on which it was received.By contrast with known search algorithms, such as A*, as described athttps://de.wikipedia.org/wiki/A*-Algorithmus, retrieved on 20 Feb. 2019,or BFS, as described at https://de.wikipedia.org/wiki/A*-Algorithmus,retrieved on 20 Feb. 2019, advantageously no state information about thesearch is stored on a satellite S or relayed to the next satellite S.

For the transmittal of data between the transmitting satellite TS, whichhas received the data packet being sent for transmission, and theparticular receiving satellite RS, a number of sequential singletransmissions is performed. Principles from Software Defined Networkingare used for the routing of the data packets within the satelliteconstellation.

No direct position information will be exchanged between the satellitesS of the satellite constellation, for example through routing protocols.The routers on board the individual satellites S within the satelliteconstellation only have information about the respective layout of thesatellite network for the routing of the data packets, such as the sizeof the network, the number of orbits O₁, . . . , O₅ or the number ofsatellite lines LOS₁, . . . , LOS₆. Furthermore, only the availabilitystatus of the immediately neighboring satellites is known to the routerson board the satellites S, since they are in a direct data link withthem. If a neighboring satellite S or its interface to a satellite S islost, this satellite S will implicitly recognize the loss in that thedata link is no longer available on the physical layer. Furthermore, nostatus information is exchanged with the lost or other satellites S.

In order to select the shortest path to the receiving satellite RS, thetransmitting satellite TS therefore first determines the coordinatevalues of the receiving satellite RS within the satellite constellationand then relays the data packet to one of the topologically neighboringsatellites S which are in direct communication with the receivingsatellite RS. Such a data transmission is understood as being a singletransmission.

“Topologically neighboring” in the context of the invention is usedmeaning that a communication exists between the respective satellites Sor flying objects F at least for a partial region of the respectiveorbit O or flight path FB. Such a permanent communication occurs, e.g.,between a satellite S and its preceding or following orbital satellite.

Outside of the polar regions, a respective satellite S is also incommunication. with its associated neighboring satellite of a right-handneighboring orbit or a left-hand neighboring orbit. The respectiveneighboring satellite S relays the data packet arriving at it once moreto one of its topologically neighboring satellites and so forth, untilthe data packet finally reaches the receiving satellite RS. In this way,the data packet is relayed in a succession of such single transmissionsfrom the transmitting satellite TS to the receiving satellite RS.

A first exemplary embodiment of a method according to the invention forthe packet transmittal of data between two satellites shall be describedin the following with the aid of FIG. 3. In the exemplary embodiment ofFIG. 3, the satellite TS with the coordinate values (1,1) obtains a datapacket and determines from its satellite-specific IP prefix that thesatellite with the coordinate values (3,3) is the receiving satelliteRS. Now, in order to transmit the data packet on the fastest path fromthe satellite S (1,1) to the satellite S (3,3), the data packet is atfirst relayed in a series of single transmissions first to theneighboring satellite S (2,1) on the orbit O₂ and the same satelliteline LOS₁. The data packet is then sent to the satellite S (2,2) on theorbit O₂ and the satellite line LOS₂, to the satellite S (3,2) on theorbit O₃ and the satellite line LOS₂ and finally to the receivingsatellite RS (3,3) on the orbit O₃ and the satellite line LOS₃.

The rules by which the data packet is sent from a transmitting satelliteTS to a particular receiving satellite RS can be learned and memorizedin the respective satellites S so that a routing path does not have tobe searched for again for subsequent data transmissions involving thesame receiving satellite RS. This will be done until such time as therouting path changes, for example, because the satellites S have crossedthe north pole NP or the south pole SP and the orbits O₁, . . . , O₅have crossed over each other, so that the mutual positions ofneighboring satellites within the satellite constellation have changed,and then the previously memorized rules are discarded and a newtransmission path to the particular receiving satellite RS isdetermined.

As a satellite S approaches the geographical north pole NP or south poleSP, for example, a communication with its associated neighboringsatellite of its right-hand, e.g., eastern neighboring orbit or itsleft-hand, e.g., western neighboring orbit is not possible, since theorbits O₁, . . . , O₅ cross each other in the region of the poles NP,SP. In this case, the method according to the invention stilladvantageously ensures a simple topological routing of the data packets,in that the data is at first relayed from the particular satellite S inthe direction of a preceding satellite or a following satellite, notlocated near the poles, from which a further routing to a topologicallyneighboring satellite on another neighboring orbit is possible with noproblems.

A second exemplary embodiment of a method according to the invention forthe packet relaying of data, in which data packets are relayed from amobile terrestrial terminal device, such as a satellite telephone,through satellites to another mobile terrestrial terminal device, shallbe described in the following with the aid of FIG. 3.

For example, if a mobile terminal device such as a satellite telephone,positioned on the earth E, connects to a satellite S of the satelliteconstellation in whose coverage territory it is located, and establishesa communication with the satellite S, a distinct communication addresswill be assigned to this terminal device by the satellite S. Forexample, this may be a distinct IP address, which remains assigned tothe terminal device, for example even when it is in the coverageterritory of another satellite S at a later time.

FIG. 3 shows a terminal device as the transmitting terminal device SE,which relays a data packet, being sent to a receiving terminal deviceEE, to the transmitting satellite TS in whose coverage territory it issituated. The data packet contains a communication address assigned tothe receiving terminal device EE and the transmitting satellite TSdetermines a receiving satellite RS which is in data communication withthe receiving terminal device EE having the respective communicationaddress.

In order to determine the receiving satellite RS, the transmittingsatellite TS in one variant can make a query to all the satellites S ofthe satellite constellation, for example, in order to determine thesatellite with which the receiving terminal device EE is currentlyregistered. In response to its query, the transmitting satellite TSreceives a message from each satellite S of the satellite constellationas to whether the particular receiving terminal device EE is currentlyregistered with it or not. This likewise involves a high data trafficbetween the individual satellites of the satellite constellation.

The individual satellites S in the satellite constellation may also bedivided into clusters C, each time determining one of the satellites Sof the cluster C to be a cluster registration satellite CREG. Such apartitioning of the satellite constellation into clusters C isrepresented in FIG. 4. The satellite constellation represented in FIG. 4contains six orbits O₁, . . . , O₆ and eleven satellite lines LOS₁, . .. , LOS₁₁. The satellites S of the satellite constellation are indicatedin FIG. 4 by their respective coordinate values within the satelliteconstellation and assembled in six clusters C, each of them comprisingmultiple satellites S. The satellites S belonging to the same cluster Care shown by the same hatching in FIG. 4. The cluster registrationsatellite CREG of each cluster C is shown by a double border each time.

The polar regions around the geographical south pole SP and thegeographical north pole NP are shown schematically in FIG. 4. As can beseen, such a partitioning of the satellite constellation into clusters Censures a flat coverage even in the polar regions.

If individual terminal devices stand in data communication with asatellite S of a cluster C, these terminal devices are advantageouslyregistered by satellites S only with the cluster registration satelliteCREG. This means that each satellite S only needs to send to the clusterregistration satellite CREG information as to which or how many terminaldevices are currently in data communication with it, which means adefinite reduction in the data traffic between the satellites S of thesatellite constellation.

The procedure for a registration of, for example, a transmittingterminal device SE that is not yet registered at the moment with anysatellite S, is as follows:

If a transmitting terminal device SE connects for example to a firstsatellite S₁, the first satellite S₁ will register the transmittingterminal device SE at the cluster registration satellite CREGresponsible for the first satellite S₁. The cluster registrationsatellite CREG now has information as to the satellites S by which thetransmitting terminal device SE can be reached. This is required inorder for a cluster registration satellite CREG to send a positiveresponse to a querying satellite S, so that new and temporarily saveddata can then be sent from the transmitting terminal device SE to thereceiving terminal device EE. The registration process for a receivingterminal device EE occurs in similar fashion.

If a satellite S moves onward, so that a terminal device with which thesatellite S was previously in communication is now no longer in itscoverage territory, a handover of the terminal device will occur throughthe cluster registration satellite CREG. This procedure is explained inthe following.

For example, a first terminal device as the transmitting terminal deviceSE is in data communication with a first satellite S₁ and a secondterminal device as a receiving terminal device EE with a secondsatellite S₂, and data packets are relayed from the transmittingterminal device SE to the receiving terminal device EE. During thisrelaying of data packets, the receiving terminal device EE switches fromthe coverage territory of the second satellite S₂ to the coverageterritory of a third satellite S₃.

If the receiving terminal device EE leaves the coverage territory of thesecond satellite S₂, the receiving terminal device EE will bederegistered by the satellite S₂ from the cluster registration satelliteCREG responsible for the second satellite S₂. The cluster registrationsatellite CREG responsible for the second satellite S₂ now no longer hasany information as to where the receiving terminal device EE is located,and neither do any other cluster registration satellites CREG in thesatellite constellation have any information about this.

The second satellite S₂ sends a message to all satellites S of allcommunication partners of the receiving terminal device EE, i.e., inthis particular instance, to the first satellite S₁, since thetransmitting terminal device SE was connected to the receiving terminaldevice EE via the second satellite S₂, and the satellites S thereupondelete their routing information for the receiving terminal device EE.

The transmitting terminal device SE now attempts to send data once moreto the receiving terminal device EE. However, the first satellite S₁ hasno routing information for the receiving terminal device EE, since thishas been deleted. Therefore, the first satellite S₁ sends a query to allcluster registration satellites CREG of the satellite constellation towhich satellite the receiving terminal device EE is connected. Duringthis period, the data from the transmitting terminal device SE to thereceiving terminal device EE is saved temporarily at the first satelliteS₁. If its queries to a cluster registration satellite CREG are notanswered, the query to this cluster registration satellite CREG will berepeated, e.g., for a maximum of three times.

The cluster registration satellites CREG respond either affirmatively,i.e., a satellite S with which the receiving terminal device EE nowstands in communication has been found by this cluster registrationsatellite CREG, or negatively, i.e., no satellite S with which thereceiving terminal device EE stands in communication could be found. Ifall cluster registration satellites CREG have responded negatively, orif no responses have been received despite repetitions, the temporarilysaved data is discarded by the first satellite S₁.

The first affirmative response of a cluster registration satellite CREGis used by the first satellite S₁ to determine the receiving satelliteRS. In the specific example, this is the third satellite S₃. All otherresponses from cluster registration satellites CREG, whether affirmativeor negative, that arrive after this first affirmative response at thefirst satellite S₁, will be ignored by it. Also, any still pendingrepetitions will be terminated. The data for the receiving terminaldevice EE temporarily saved by the first satellite S₁ will then berouted to the third satellite S₃ as the receiving satellite RS.

If a satellite S sends a message to all satellites S of allcommunication partners of a receiving terminal device EE that thereceiving terminal device EE is no longer in communication with it, thecommunication between the transmitting terminal device SE and thereceiving terminal device EE will be interrupted, but the data beingrouted will be saved temporarily.

Such a process generally lasts for only a few 100 milliseconds, forexample. The waiting time for the response of the cluster registrationsatellites CREG or the number of repetitions of the queries and thewaiting time between repetitions may be chosen such that no data lossoccurs during the time window between the reporting that the receivingterminal device is no longer in communication with a particularsatellite S and an affirmative response of a cluster registrationsatellite CREG.

The method is symmetrical, i.e., the described process also holds for arelaying of data from the receiving terminal device EE to thetransmitting terminal device SE.

Now, if a data transmission is to occur between two terminal devices viathe satellite constellation, the transmitting satellite TS canespecially easily determine the receiving satellite RS in datacommunication with the receiving terminal device EE, as compared to thepreviously described variant of a query sent to all satellites S of thesatellite constellation, since the transmitting satellite TS only needsto send such a query to the individual cluster registration satellitesCREG of the satellite constellation. This procedure advantageouslyresults in a further reduction in the data traffic between thesatellites S of the satellite constellation.

If a cluster registration satellite CREG has information that thereceiving terminal device EE is in data communication with a satellite Sassociated with the cluster C of the cluster registration satelliteCREG, the cluster registration satellite CREG will relay the coordinatevalues of this receiving satellite RS to the transmitting satellite TS.The transmitting satellite TS then establishes a data link with thereceiving satellite RS having so reported, in order to produce the datacommunication.

The data packet being relayed is sent, as previously described, in aseries of single transmissions, as has been already described, to thereceiving satellite RS, from which the data packet is further relayed tothe receiving terminal device EE on the earth E.

If a terminal device leaves the coverage territory of a particularsatellite S, it will send information about this to the clusterregistration satellite CREG. The particular satellite S also sends thismessage to all other satellites S which are serving a receiving terminaldevice EE with which the transmitting terminal device SE was incommunication.

In addition or alternatively, the cluster registration satellite CREGcan in this case relay messages to the other satellites S in whosecoverage territory are located terminal devices that are currently indata communication with the particular terminal device. If the clusterregistration satellite CREG also sends this information in addition tothe respective satellite S, this will contribute to increasing thereliability.

The respective satellites S will remove the information saved regardingthe routing path to this terminal device and make a new query to thecluster registration satellite CREG as to which of the satellites S ofthe cluster C the terminal device is currently in data communication.

FIG. 5 shows a schematic representation of a swarm of flying objects F,such as can be used for a method of packet transmission of dataaccording to the invention. In the exemplary embodiment in FIG. 5, theflying objects F are high-altitude platform stations or high-altitudepseudo-satellites (HAPS) flying in a dynamic constellation, i.e.,unmanned flying objects, such as are described for example athttps://en.wikipedia.org/wiki/High-altitude_platform_station, retrievedon 28 Feb. 2019. Such high-altitude platform stations can form dynamicconstellations, where the swarm geometry can be used to determine thecoordinate values for the routing of data packet, as is described inFIG. 2 and FIG. 3 for the exemplary embodiment with a satelliteconstellation.

Such a swarm of flying objects F may be used, for example, to provide anetwork connectivity for the first time in remote regions of the earthor to provide a temporary network connectivity for rescue efforts on theground during a crisis situation, such as a natural disaster.

The flying objects F each move within the given swarm of flying objectsF, as can be seen in FIG. 5, on closed flight paths FB₁, . . . , FB₃,for example, and they are arranged in a grid characterized by a numberof flight paths FB₁, . . . , FB₃ and lines of flying objects LOF₁, . . ., LOF₃. In the same way as was explained above for an exemplaryembodiment with a satellite constellation per FIG. 1 to 4, each time anumber of flying objects F are arranged at equal distances in successionon each flight path FB₁, . . . , FB₃ in a swarm of flying objects F.Each of these flying objects F is in communication respectively with apreceding flying object and a following flying object.

Furthermore, the individual flying objects F of a flight path FB₁, . . ., FB₃ are associated respectively with an associated neighboring flyingobject of a right-hand neighboring flight path looking in the flightdirection and an associated neighboring flying object of a left-handneighboring flight path looking in the flight direction, with which therespective flying object is in communication at least for a portion ofthe flight path FB₁, . . . , FB₃. At the margins of the swarm, theparticular flying objects F, as previously explained for the satelliteconstellation, are only in communication with a right-hand or left-handneighboring flying object.

As can be seen in FIG. 5, each of the flying objects F is assignedcoordinate values within the swarm based on its position within the gridof flight paths FB₁, . . . , FB₃ and flying object lines LOF₁, . . . ,LOF₃. In the exemplary embodiment shown in FIG. 5, there are twocoordinate values which indicate a two-dimensional position within theswarm. Alternatively, the actual geoposition of the individual flyingobjects F can be used, i.e., the longitude and latitude of its currentposition.

With a method according to the invention, by means of such a swarm offlying objects F, data packets can be relayed between mobile and/orstationary terminal devices through the flying objects F of the swarm.

In the exemplary embodiment of FIG. 5, for example, the flying object Fwith the coordinate values (1,2) obtains a data packet from a mobiletransmitting terminal device SE and determines from the data beingrouted that the flying object with the coordinate values (3,3) is thereceiving flying object RF. Now, in order to send the data packet on thefastest path from the flying object (1,2) to the flying object (3,3),the data packet is relayed at first in a series of single transmissionsto the neighboring flying object F (1,3) on the same flight path FB₁ andthe neighboring flying object line LOF₃. The data packet is then relayedto the flying object F (2,3) on the flight path FB₂ and the flyingobject line LOF₃, and finally to the receiving flying object (3,3) onthe flight path FB₃ and the flying object line LOF₃.

In the same way as was described above for a satellite constellation,the flying objects F of a swarm can also be divided into clusters, eachtime one of the flying objects F of the cluster being determined to be acluster registration flying object. If individual terminal devices arein data communication with a flying object F of the cluster, theseterminal devices will advantageously only be registered by the flyingobjects F at the cluster registration flying object and datatransmission or queries regarding the registration of terminal devicescan be done also for flying objects in the manner already described forsatellites.

Alternatively, such a swarm of flying objects F may also be a droneswarm, for example.

The invention claimed is:
 1. A method for packet transmission of databetween at least two terminal devices via at least one flying object,wherein: flying objects are moving within a given swarm of the flyingobjects; the swarm of flying objects having a plurality of the flyingobjects which are respectively moving on flight paths; the flyingobjects are disposed in a grid being characterized by a number of theflight paths; a number of the flying objects are moving in succession oneach flight path, so that each of the flying objects of the flight pathis in respective communication with a preceding flying object and afollowing flying object; the flying objects are moving on multiple onesof the flight paths such that each time there are disposed in a givenorientation to a respective flight path an associated neighboring flyingobject of a right-hand neighboring flight path looking in a flightdirection and an associated neighboring flying object of a left-handneighboring flight path looking in the flight direction, they are incommunication with a respective flying object for at least a portion ofthe flight path; which comprises the steps of: determining one flyingobject from the swarm of the flying objects to be a reference flyingobject; assigning each of the flying objects a position, the assigningstep further comprises the substeps of; wherein the flying objects whichare situated on a same flight path are assigned a same coordinate valueof a first coordinate; wherein the flying objects which are incommunication with each other as associated neighboring flying objectsof the left-hand and the right-hand neighboring flight path are assigneda same coordinate value of a second coordinate; deriving coordinatevalues of a receiving flying object within the swarm of the flyingobjects from a respective data packet being transmitted; performing anumber of sequential single transmissions for a transmittal of databetween a transmitting flying object and the receiving flying object,wherein each single transmission within the swarm of the flying objectsoccurs only between two respective flying objects which aretopologically neighboring and in direct communication with each other;and during a process of the single transmission from the respectiveflying object where the data packet is located that is beingtransmitted, a topologically neighboring flying object is selected withan aid of which a coordinate value of the receiving flying object whichis derivable from the data packet is selected and the data packet issent to a selected neighboring flying object; and bringing the at leasttwo terminal devices positioned on ground into communicationrespectively with at least one of the flying objects from the swarm ofthe flying objects, each of the terminal devices being assignedrespectively one communication address; sending the data packet from oneof the terminal devices functioning as a transmitting terminal device toa respective other one of the terminal devices functioning as areceiving terminal device, the data packet containing the communicationaddress assigned to the receiving terminal device; relaying the datapacket by the transmitting terminal device to one of the flying objectsas the transmitting flying object; determining the receiving flyingobject by the transmitting flying object, which stands in datacommunication with the receiving terminal device; relaying the datapacket from the transmitting flying object to the receiving flyingobject; and relaying the data packet from the receiving flying object tothe receiving terminal device; and dividing the flying objects of theswarm of the flying object into clusters, each time one of the flyingobjects of the cluster being determined to be a cluster registrationflying object; registering the terminal devices which stand in datacommunication with a flying object of the cluster through the flyingobject with the cluster registration flying object; establishing a datalink in an event that the data link is to be established with thefurther sub-steps of: sending a query from the transmitting flyingobject to individual cluster registration flying objects as to whether aparticular receiving terminal device stands in the data link with theflying object associated with the cluster registration flying object;and sending back any coordinate values of the receiving flying objectregarding the query by the cluster registration flying object to thetransmitting flying object based on the query; and establishing the datalink by the transmitting flying object to the receiving flying objecthaving so reported back, in order to bring about the data communication.2. The method according to claim 1, wherein: the flight paths are closedflight paths; the flying objects moving in succession are equidistantfrom each other; the position is a two-dimensional position containingtwo coordinate values within the swarm of the flying objects based onits position relative to the reference flying object; and thetopologically neighboring flying object is a neighboring flying objector preceding flying object or following flying object.
 3. The methodaccording to claim 1, wherein the communication address is a distinctaddress.
 4. The method according to claim 1, wherein the coordinatevalues are two-dimensional coordinate values.
 5. A method for packettransmission of data between at least two terminal devices via at leastone satellite from a group of satellites, wherein: the satellites aremoving within a given satellite constellation around earth; the givensatellite constellation contains the satellites are respectively movingon a non-geostationary orbit around the earth; individual ones of thesatellites are disposed in a grid which is characterized by a number oforbits; and an orbit extends respectively in a circle or ellipse aroundthe earth; which comprises the steps of: moving a number of thesatellites in succession on each of the orbits, so that each of thesatellites of the orbit, is in respective communication with a precedingorbital satellite and a following orbital satellite; moving thesatellites on multiple said orbits, such that each time there aredisposed in a given orientation to a respective orbit an associatedneighboring satellite of a right-hand neighboring orbit looking in aflight direction and an associated neighboring satellite of a left-handneighboring orbit looking in the flight direction and are incommunication with a respective satellite for at least a portion of theorbit; determining one satellite from the given satellite constellationto be a reference satellite; assigning each of the satellites aposition, the assigning step includes the substeps of; assigning thesatellites which are situated on a same orbit a same coordinate value ofa first coordinate; assigning the satellites which are in communicationwith each other as associated neighboring satellites of the left-handand the right-hand neighboring orbit a same coordinate value of a secondcoordinate; deriving coordinate values of a receiving satellite withinthe given satellite constellation from a respective data packet beingtransmitted; performing a number of sequential single transmissions forthe transmittal of data between a transmitting satellite and thereceiving satellite, wherein each single transmission within the givensatellite constellation occurs only between two respective saidsatellites which are topologically neighboring and in directcommunication with each other; and selecting, during a process of thesingle transmission from a respective satellite where the data packet islocated that is being transmitted, a topologically neighboring satellitewith an aid of which the coordinate value of the receiving satellitewhich is derivable from the data packet is selected and the data packetis sent to a selected neighboring satellite; and bringing at least twoterminal devices positioned on ground into communication respectivelywith at least one of the satellites of the given satelliteconstellation, each of the terminal devices being assigned respectivelyone communication address; sending the data packet from one of theterminal devices as a transmitting terminal device to a respective otherone of the terminal devices as a receiving terminal device, the datapacket containing a communication address assigned to the receivingterminal device; relaying the data packet by the transmitting terminaldevice to one of the satellites as a transmitting satellite; determininga receiving satellite by the transmitting satellite, which stands indata communication with the receiving terminal device; relaying the datapacket from the transmitting satellite to the receiving satellite; andrelaying the data packet from the receiving satellite to the receivingterminal device; and diving individual ones of the satellites of thegiven satellite constellation into clusters, each time one of thesatellites of the cluster being determined to be a cluster registrationsatellite; registering individual ones of the terminal devices whichstand in data communication with a satellite of the cluster through thesatellite with the cluster registration satellite; establishing a datalink in an event that the data link is to be established by the substepsof: sending a query from the transmitting satellite to individual onesof cluster registration satellites as to whether a particular receivingterminal device stands in the data link with the satellite associatedwith the cluster registration satellite; and sending back any coordinatevalues of a receiving satellite regarding the query back by the clusterregistration satellite to the transmitting satellite based on the query;and establishing the data link by the transmitting satellite to thereceiving satellite having so reported back, in order to bring about thedata communication.
 6. The method according to claim 5, wherein: theorbit extends on one side of the earth from a first pole to an oppositesecond pole and then on an other side of the earth from the second poleto the first pole; the satellites moving in succession are equidistantfrom each other; the position is a two-dimensional position having twocoordinate values within the given satellite constellation based on itsposition relative to the reference satellite; and the topologicallyneighboring satellite is a neighboring satellite or a precedingsatellite or a following satellite.
 7. The method according to claim 5,wherein the communication address is a distinct address.
 8. The methodaccording to claim 5, wherein the coordinate values are two-dimensionalcoordinate values.